Industrial Wastewater Treatment Systems: Reduce Your Risk with Proactive Assessments
January 30, 2019
By John Wentz, P.E.
Senior Project Engineer, Environmental Division
This article was originally published in Currents, POWER’s quarterly Environmental newsletter.
At the end of a production process, hidden at the back of the lot where nobody likes to go, sits an industrial wastewater treatment plant (WWTP). The WWTP collects the facility’s process wastewater—a by-product of the production process—and treats it to a quality suitable for discharge on a continuous and consistent basis.
Just like the production facility, the WWTP is designed with specific operating criteria and requires periodic assessment. A properly run and compliant WWTP may receive little, if any, attention until discharge compliance issues arise.
Failure to properly treat wastewater to the minimum requirements of the discharge permit will cause a facility to be identified as non-compliant. This status can result in unnecessary expenses, unwanted public and regulatory scrutiny, and potentially a production shutdown leading to loss of revenue. Implementing a more proactive approach can be a smart move to reduce risk and control costs.
Periodic assessments can help identify and address conditions that could potentially lead to treatment failures and non-compliance. Beyond the necessary mechanical maintenance, there are two proactive timeframes where an assessment should be considered:
- Production changes
- Discharge permit renewals
Since one of the above timeframes is linked to permit renewals, it is important to understand your requirements. WWTPs typically fall under two types of discharge classifications: indirect or direct.
The majority of processing and manufacturing facilities discharge into public sewers and are known as indirect dischargers. The process wastewater is often contaminated by a variety of organic and inorganic constituents that are harmful to the public sanitary sewer collection system, and therefore requires a WWTP (or pretreatment facility as commonly known for indirect dischargers).
The discharge from a pretreatment facility is required to meet wastewater treatment standards specified in the discharge permit, which is typically issued by the local publicly owned treatment works (POTW) facility. The POTW receives the wastewater from the pretreatment facility (along with all other industrial and domestic wastewaters from the sewer-shed), provides further treatment and then safely discharges the wastewater into the environment.
Processing and manufacturing facilities located in areas where public sewers are not available can be permitted to discharge directly into a receiving body of water such as a lake, stream or river and are known as direct dischargers. To do so, they need a direct discharge permit that is typically issued at the state level and is based on site-specific water quality objectives.
Since the discharge goes directly to the environment, the level of treatment for a direct discharger is typically more stringent than that of an indirect discharger, and the penalties for non-compliance are more severe.
How can you proactively prevent non-compliance issues from developing?
The scenario to avoid is waiting until the wastewater discharge is out of compliance and you are forced into a reactive mode of investigation and reporting. The subsequent fines and corrective action to resolve the issue, and prevent a reoccurrence, is a costly consequence.
As the old saying goes, an ounce of prevention is worth a pound of cure. Consider these key timeframes as ideal checkpoints to evaluate your WWTP/pretreatment facility. These are proactive measures intended to prevent conditions that will lead to non-compliance.
An industrial WWTP is designed within defined hydraulic loading and mass loading parameters for specific inorganic and organic constituents. Changes in production can lead to a difference in the influent wastewater volume and quality outside of the design basis, resulting in reduction of the WWTP treatment efficiency.
Such changes may include an increase or decrease in production quantity, items produced, processing equipment, raw materials, cleaning procedures and frequency, production and/or cleaning chemicals, facility expansion or reduction, personnel, procedures, and any other changes that may impact the volume and/or constituent loadings of wastewater from the production and manufacturing operations.
Consider this: if the raw materials change in a production process, will the finished product remain unchanged? Of course not. So, thinking of your WWTP as a process system, with the desired output consisting of compliant wastewater discharge, makes it clear that any production change will result in a change to the final product.
An assessment prior to production changes can provide valuable insight about the potential impact these changes could have on the WWTP. With advanced planning, these impacts can be mitigated or the design can be adjusted to ensure the WWTP remains in compliance.
Discharge permit renewals
Pretreatment Facility Discharge Permit Renewal. As an indirect discharger, the discharge permit for your pretreatment facility is typically valid for a period of three to five years and requires a renewal application be submitted typically six months in advance of the permit expiration date.
During the permit renewal process for your facility, it is advised to check in with appropriate POTW personnel. If the POTW has changes in its permit, the implementation of those changes could impact the discharge requirements of your pretreatment facility.
POTW Discharge Permit Renewal. Similar to an industrial facility, the POTW must re-apply for their National Pollutant Discharge Elimination System (NPDES) permit for direct discharge on a frequency regulated by the state. These permit limits are based upon the residential and industrial customers discharging to the POTW, treatment capabilities of the POTW and the receiving body of water.
Changes, or lack thereof, to treatment operations at the POTW can have positive or negative repercussions on the requirements of industrial wastewater discharge from your pretreatment facility. For example, a POTW that is close to reaching its design capacity, and cannot implement needed upgrades, may reduce the allowable discharge limits of your pretreatment facility, as well as others that discharge to that POTW.
On the other hand, if the POTW facility expands or adds additional steps to the treatment process, their treatment capabilities are improved, which may allow more hydraulic volume and/or higher mass loadings from your pretreatment facility and others discharging to the POTW.
Advanced knowledge of this information allows for planning ahead of your facility’s specific permit renewal. Evaluating your system against these changes in the discharge requirements will identify if changes to your pretreatment facility are needed.
Direct Discharge Permit Renewal Under State NPDES. If your facility is a direct discharger, contact with the state regulatory personnel would be appropriate to determine if there have been any changes to the designation of the water body, complaints from the public or modifications to other regulations.
Keeping back-end utilities top of mind
The utilities that serve the back-end of the facility operations can often be an afterthought. With a little planning and one or two proactive steps, WWTP owners can be better prepared for inevitable changes to their wastewater treatment system—and are more likely to avoid a scramble to stay in compliance when those changes come.
About the Author:
As a seasoned veteran Project Engineer, Project Manager and Engineering Department Manager, John has performed engineering and managed projects for the private and government sectors. His core competencies include high-quality water production, water and wastewater management, industrial wastewater treatment assessment and design, beneficial use, water sustainability programs, and environmental compliance. John has also performed environmental emergency response on immediately threatening situations to water resources and has provided project management on government environmental restoration and improvement projects. Do you have questions for John? Send him an email at firstname.lastname@example.org.